Railway freight cars may be used to transport bulk materials. In transporting such goods, it is desirable to provide railway cars that are efficient with respect to their cost, ease of manufacture, and energy required to move the cars throughout the railway system. Prior art cars have made advances with respect to making cars stronger, lighter in weight, easier to manufacture, and more aerodynamic, but the search continues for improved railway cars that are more efficient in these regards while also increasing the volume.
Hopper cars may be used to transport perishable goods and materials such as grain, corn, and other dry granular commodities. Frequently, a covered hopper car may be used for this purpose. Such hopper cars typically include a roof having an access hatch that is used to load the hopper car. In such railway cars, the roof may be connected to the side by means of a side plate or top chord. With respect to prior art covered hopper cars, a concern was raised that rain water and other liquids may migrate to the interior of the hopper car and potentially destroy or damage portions of the cargo.
In designing hopper cars and other railway cars, it is desirable to maximize the volume of the car. While maximizing the volume is a goal that may be achieved by minimizing the thickness of the sidewalls, the sidewalls must remain strong and durable. The side posts, or side stakes, must carry a load from the roof but also stiffen the side sheets to help carry lateral loads and beam loads. Frequently, cars, such as covered hopper cars, will have numerous side posts spaced along the side of the car to provide support. Conventional hopper cars have required as many as 34 or more side posts per car. Numerous side posts increase the material cost and complexity of the design of the railway car. Additionally, when the side posts are placed on the outside of the side sheet, the side posts, which are frequently rectangular shaped, increase the aerodynamic drag on the car, and thereby, reduce the car's efficiency.
As previously noted, it is desirable to maximize the volumetric capacity of a hopper car. In addition to maximizing the volume of the car, however, the car must be designed to allow for easy and efficient unloading of the cargo or loading through the hopper doors. To facilitate unloading, many conventional hopper cars have angled hopper chutes with a steep incline. In these conventional cars, the incline of the hopper chutes has frequently been 45.degree. or more. This steep of an angle reduces the volume but allows for easy discharge of the cargo.